1. Field of the Invention
The present invention relates generally to a hard disk drive and, more particularly, to a hard disk drive including a mechanism that reduces electric magnetic interference (EMI) in the hard disk drive.
This application claims priority under 35 U.S.C. §119 from Korean Patent Application No. 10-2005-0125038, filed on Dec. 19, 2005, in the Korean Intellectual Property Office, the entirety of which is hereby incorporated by reference.
2. Description of Related Art
Hard disk drives (HDDs) are memory devices that are used to record and reproduce data by converting digital electric pulses to a magnetic field. This conversion of data from a digital form to a magnetic field makes the data more permanent. HDDs include various electronic and mechanical components to perform the functions of recording and reproducing data. While HDDs have many applications, HDDs are, widely used as auxiliary memory devices of computer systems because of their ability to provide quick access to large amounts of data.
With the recent increase in TPI (tracks per inch) and BPI (bits per inch), the capacity of HDDs has increased. This increase in capacity has increased the fields in which HDDs may be used. For example, a compact HDD having a diameter of 0.85 inches, i.e., a size similar to that of a coin, has been developed recently and is expected to be used in mobile phones in the future. While a HDD has various uses, the HDD is more susceptible to vibrations and shocks compared to other memory devices. Various efforts have been directed towards studying and remedying this problem.
FIG. 1 is an exploded perspective view of a conventional HDD. Referring to FIG. 1, a conventional HDD includes a base 110 and a cover 130. The cover 130 is used to shield an upper opening portion of the base 110. A plurality of internal parts related to reading and writing of information are installed on the base 110, which will be described later. For example, a disk 112 for recording and storing data and a head stack assembly (HSA) 116 for reading or writing information on the disk 112 while moving across the disk 112 are installed on the base 110.
The base 110 includes many internal parts. Furthermore these internal parts operate based on predetermined signals. Therefore, these internal parts produce electromagnetic waves. These electromagnetic waves may be transmitted as electromagnetic energy to other devices that are located near the internal parts. In particular, the electromagnetic energy may be transferred to the other devices by means such as, for example, conduction and radiation. Furthermore, this electromagnetic energy, which is also known as electromagnetic interference (EMI) may damage the other devices and thus affect the performance of the apparatus that includes the HDD and these other devices. The apparatus may include electronic equipment such as, for example, a computer and a notebook.
As shown in FIG. 1, a cover 130 is coupled to the upper surface of the base 110 to protect the internal parts. Specifically, the cover 130 is coupled to the base 110 using six screws 138. Because of the coupling of the cover 130 to the base 110, an electromagnetic wave generated by the internal parts is shielded. Generally, as shown in FIG. 1, the cover 130 is coupled to the base 110 using a total of the six screws 138. Specifically, three screws each are used along each, of the longer side of the cover 130.
However, when the cover 130 is coupled to the base 110 using the six screws 138 as shown in FIG. 1, the effect of preventing the EMI is low. In particular, an electromagnetic wave is generally emitted from a preamplifier 126 installed on the HSA 116 or a flexible printed circuit (FPC) 128 connecting the preamplifier 126 to a printed circuit board assembly (PCBA) 125. The effect of shielding the electromagnetic wave generated in the vicinity of the HSA 116 using the six screws 138 is relatively low.
To solve the above-mentioned problem, according to another conventional HDD, as shown in FIG. 2, an additional screw 138a is further provided in the center area of a short side of the cover 130. This is the area where the HSA 116, which is the most sensitive portion of the HDD, is located. Thus, a total of seven screws—138 and 138a, are used to fix the cover 130 to the base 110.
However, the conventional HDD has a number of shortcomings. For example, as shown in FIG. 2, when the number of the screws 138 and 138a for a single HDD increase, the cost of assembling the HDD rises. Furthermore, the time taken to couple the cover 130 to the base 110 increases. Furthermore, because a gasket (not shown) is also installed between the base 110 and the cover 130 as a means to closely combine the cover 130 and the base 110, when the screw 138a is also used as shown in FIG. 2, the shape and structure of the gasket needs to be changed. This modification of the gasket may increase the complication of the HDD assembly process because of an increase in the time and effort required to install the gasket.